The present invention relates to techniques for acoustically scanning the interior of a volume and more specifically for presenting visual images of the material using scan techniques commonly referred to as B-scan, C-scan and scanned acoustical holography.
Such techniques are presently being utilized in varying degrees for medical diagnosis and for nondestructive testing of optically opaque materials (liquids and solids) in which an acoustical pulse transmitter/receiver is scanned over the material. Generally the images from the B-scan and C-scan techniques are displayed on a cathode ray tube (CRT) in two dimensional form with B-scan display systems showing a two dimensional depth cross section (X-Z plane or Y-Z plane) and the C-scan display system showing a two dimensional plan view (X-Y plane). In both systems the lapsed time of the acoustical pulse traveling from the transmitter to the attenuated surface or internal discontinuity back to the receiver and the amplitude of the reflected acoustical signal are measured. Examples of such techniques are disclosed in the Becker et al U.S. Pat. No. 3,792,423 granted February, 1974. A scanned holographic system is disclosed in the Collins et al U.S. Pat. No. 4,021,771 granted May, 1977.
One of the principal shortcomings of such scanning is the excessive time required to effectively scan the volume to form a hologram, either in physical or electronic form. A further shortcoming of such scanning technique is the difficulty of acoustically scanning the interior of an object having a contoured surface.
One of the principal objects of this invention is to provide a unique scan acoustical holographic apparatus to overcome the objections cited above.
Other advantages of this invention will become apparent upon reading the following detailed description of a preferred embodiment.